Arup had been appointed by the Landesbetrieb Straßenbau North Rhine-Westphalia for the assessment and planning of the strengthening measures for the deck and bearings of the Ottfingen Viaduct along the A 45 motorway in Germany.
The post tensioned concrete bridge has a 235m long deck with a T-beam cross section. The deck was constructed span by span in 1970 and is longitudinally and transversely post tensioned. The bridge has seven spans, with internal lengths of 35m.
The recalculation was carried out based on the current guideline for recalculation of bridges in Germany, together with the DIN Fachbericht, which was the design code at that time, it is a summary of the applicable Eurocodes together with National Appendices. All relevant checks including ultimate limit state, serviceability limit state as well as fatigue checks were carried out.
Based on the results of the recalculation we designed the required strengthening works in longitudinal direction by means of introducing external pre-stress. The tendons are anchored with reinforced concrete blocks which are stressed to the webs of the girders.